1. Field of the Invention
The present invention relates to measuring instruments, and particularly to a digital frequency measuring device for measuring area of strip materials in the course of rolling-up thereof.
The invention is applicable in the paper and pulp industry, chemical industry, and the textile industry for measuring area of strip materials being rolled up.
2. Description of the Prior Art
In the modern production of strip materials there is a need for measuring devices capable of simultaneously measuring with a high accuracy the area of several different-size strip products in the course of rolling-up thereof, and which measuring devices can be readily checked for their precision in operation.
The existing measuring devices, and in particular digital-frequency meters do not fully conform to these requirements.
Known in the art, for instance, is an area meter for measuring area of strip materials being rolled up on a plano-cutting machine (cf. USSR Inventor's Certificate No 434,383, Int. Cl. G 05 D 3/08), which comprises a sectionalized displacement pulse-type pick-up, breakage and cut sensors, a control signal unit of the cutting machine drive, a size selector switch, and area meter fitted with a dial indicator.
The above measuring device, however, has a number of disadvantages. First, apart from the fact that sectionalized pulse-type displacement pick-ups having a high resolving power are complex to manufacture, this device is not capable of being rapidly adjusted to the sizes which are not provided for in the construction thereof, should these sizes prove desirable. Readjustment of the device in such a case involves a reduction gear with a special gear ratio related to the scale used. Second, the presence of several registering devices incorporated in the above device (the number of the registering devices being taken according to the number of different-size strip products being simultaneously rolled up) makes the construction thereof complex.
In addition, the above measuring device records values in units of area, which is effected by measuring length by the displacement pick-ups directly in the units of area. This is realized by selecting an adequate gear ratio and the number of orifices in the cylindrical body of the displacement pick-ups, which makes it impossible to check and control the measurement accuracy of the measuring device in operation.
There is also known a digital frequency area meter for measuring area of strip materials being rolled-up on a plano-cutting machine (cf. USSR Inventor's Certificate No 304,324, Int. Cl. D 21 G 9/00), comprising a length meter, a breakage sensor, a means for cutting off the strip product from the roll, a process blocking circuit, a size selector switch, and an output counter unit incorporating a clearing circuit. The process blocking circuit has inputs connected to the outputs of the pick-ups, an output connected to an input of a controlled frequency divider having a control input connected to outputs of the size selector switches, and an output connected to the output registering device.
In operation the pulses generated by the length meter are applied through the process blocking circuit to the count-input of the controlled frequency divider having its control inputs switched by the size selector switches so that, in response to a train of pulses applied to its input, at its output there appear pulses whose number is equal to the area of the strip material in the roll.
This measuring device has a low precision of measurement, which is accounted for by the fact that for obtaining a required scale spacing of the output pulse in the controlled frequency divider there is generated one output pulse from the train of pulses applied to its input. Thus, the resolving power of the device is much lower than that of the length meter. The extent of this "rounding-off" depends on the width of the strip material being rolled up. In addition, this device cannot be checked for measurement precision during operation. The presence of several controlled frequency dividers and output counter devices in the case of simultaneously controlling several different-size rolls makes the construction of this device complex.
The above area meter for measuring area of strip materials may incorporate a means for cutting off the strip product from the roll (cf. USSR Inventor's Certificate No 338,580, Int. Cl. D 21 G 9/00), which means comprises a paper level pick-up for indicating the level of the paper in the roll, a control unit, and a memory unit. The level pick-up is made in the form of a magnetic head whose recording input and reading output are connected to the control unit. The level pick-up is mounted on the shaft of the cutter of the reeling mechanism, while the memory unit is a magnetic tape fixed perpendicularly to the axis of said shaft.
In the case of breakage of the strip product being rolled up a corresponding mark is recorded on the magnetic tape by a recording pulse from the magnetic head. The deformed portion of the product, resulting from the breakage thereof, is cut off by the operator. In this case the area-measuring device will operate again only when the mark indicative of the breakage recorded on the tape reaches a magnetic pick-up head.
The operational accuracy of the above cutting device is not sufficient which is due to that the cutter shaft with the magnetic head of the paper level pick-up vibrates relative the magnetic tape, with the vibration amplitude being within the range from 1 to 2 mm. In addition, the application of this measuring device is limited because the paper level pick-up incorporated in this measuring device is applicable only on the reeling machines wherein the material being rolled is engaged from above.